There are numerous cases when people want to know when children, employees, friends, vehicles (e.g., buses, trains, cars, etc.), etc., arrive or depart or just linger at a specific location, and also want to be notified immediately when the arrival, departure, or lingering event occurs. However, in all other cases, the location could remain private. For example, parents want to know if a child left the school perimeter in the middle of the day (e.g., during workdays only), a parent wants to know if a son is driving on the highway on a rainy night, or a teenager wants to know when a friend arrives at any mall during weekends.